Mascara brush



FIG. 1 is a front left perspective view of a mascara brush showing my new design;

FIG. 2 is a left elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right elevation view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a front end view thereof, enlarged to depict my design more clearly; and,

FIG. 7 is a rear end view thereof, enlarged to depict my design more clearly.

The dash-dot-dash lines immediately adjacent to the shaded areas of the mascara brush represent unclaimed boundaries of the claimed design. The dot-dot lines showing the remainder of the mascara brush are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a mascara brush, as shown and described. 